From 9005b9f4301fbb3985b507aa7d7b43c79bd94c81 Mon Sep 17 00:00:00 2001
From: sed-i <bing@sed-i.org>
Date: Tue, 6 Jan 2026 03:04:35 +0800
Subject: [PATCH] feat(stage-*): performance overlay & markdown stress test
 (#838)

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Neko <neko@ayaka.moe>
---
 apps/stage-tamagotchi/src/main/index.ts       |   4 +-
 .../src/main/windows/devtools/index.ts        |  67 +++
 .../src/main/windows/settings/index.ts        |   9 +-
 .../windows/settings/rpc/index.electron.ts    |  13 +-
 apps/stage-tamagotchi/src/renderer/App.vue    |   2 +
 .../src/renderer/layouts/settings.vue         |   4 +
 .../pages/devtools/lag-visualizer.vue         |  24 +
 .../pages/settings/system/developer.vue       |  21 +-
 apps/stage-tamagotchi/src/shared/eventa.ts    |   1 +
 apps/stage-web/package.json                   |   1 +
 apps/stage-web/src/App.vue                    |   4 +
 .../Devtools/PerformanceOverlay.vue           | 127 +++++
 .../composables/perf/register-lag-sampler.ts  | 128 +++++
 .../pages/devtools/performance-visualizer.vue | 116 +++++
 .../src/pages/settings/system/developer.vue   |  12 +
 apps/stage-web/src/stores/devtools-lag.ts     | 273 ++++++++++
 packages/i18n/src/locales/en/settings.yaml    |   6 +
 .../src/locales/en/tamagotchi/settings.yaml   |   8 +
 .../stage-layouts/src/layouts/settings.vue    |   8 +
 .../src/pages/devtools/markdown-stress.vue    | 159 ++++++
 packages/stage-shared/src/export-csv.ts       |  28 ++
 packages/stage-shared/src/index.ts            |   2 +
 packages/stage-shared/src/perf/tracer.ts      | 154 ++++++
 packages/stage-ui/src/composables/markdown.ts |  90 +++-
 packages/stage-ui/src/stores/chat.ts          |  45 +-
 .../stage-ui/src/stores/markdown-stress.ts    | 467 ++++++++++++++++++
 .../src/stores/mods/api/context-bridge.ts     |  36 +-
 .../stage-ui/src/stores/perf-tracer-bridge.ts | 142 ++++++
 pnpm-lock.yaml                                |   3 +
 29 files changed, 1918 insertions(+), 36 deletions(-)
 create mode 100644 apps/stage-tamagotchi/src/main/windows/devtools/index.ts
 create mode 100644 apps/stage-tamagotchi/src/renderer/pages/devtools/lag-visualizer.vue
 create mode 100644 apps/stage-web/src/components/Devtools/PerformanceOverlay.vue
 create mode 100644 apps/stage-web/src/composables/perf/register-lag-sampler.ts
 create mode 100644 apps/stage-web/src/pages/devtools/performance-visualizer.vue
 create mode 100644 apps/stage-web/src/stores/devtools-lag.ts
 create mode 100644 packages/stage-pages/src/pages/devtools/markdown-stress.vue
 create mode 100644 packages/stage-shared/src/export-csv.ts
 create mode 100644 packages/stage-shared/src/perf/tracer.ts
 create mode 100644 packages/stage-ui/src/stores/markdown-stress.ts
 create mode 100644 packages/stage-ui/src/stores/perf-tracer-bridge.ts

diff --git a/apps/stage-tamagotchi/src/main/index.ts b/apps/stage-tamagotchi/src/main/index.ts
index 33f503cd5..d5d387edd 100644
--- a/apps/stage-tamagotchi/src/main/index.ts
+++ b/apps/stage-tamagotchi/src/main/index.ts
@@ -20,6 +20,7 @@ import { setupAboutWindowReusable } from './windows/about'
 import { setupBeatSync } from './windows/beat-sync'
 import { setupCaptionWindowManager } from './windows/caption'
 import { setupChatWindowReusableFunc } from './windows/chat'
+import { setupDevtoolsWindow } from './windows/devtools'
 import { setupMainWindow } from './windows/main'
 import { setupNoticeWindowManager } from './windows/notice'
 import { setupSettingsWindowReusableFunc } from './windows/settings'
@@ -82,6 +83,7 @@ app.whenReady().then(async () => {
 
   // BeatSync will create a background window to capture and process audio.
   const beatSync = injeca.provide('windows:beat-sync', () => setupBeatSync())
+  const devtoolsMarkdownStressWindow = injeca.provide('windows:devtools:markdown-stress', () => setupDevtoolsWindow())
 
   const chatWindow = injeca.provide('windows:chat', {
     dependsOn: { widgetsManager },
@@ -89,7 +91,7 @@ app.whenReady().then(async () => {
   })
 
   const settingsWindow = injeca.provide('windows:settings', {
-    dependsOn: { widgetsManager, beatSync, autoUpdater },
+    dependsOn: { widgetsManager, beatSync, autoUpdater, devtoolsMarkdownStressWindow },
     build: async ({ dependsOn }) => setupSettingsWindowReusableFunc(dependsOn),
   })
 
diff --git a/apps/stage-tamagotchi/src/main/windows/devtools/index.ts b/apps/stage-tamagotchi/src/main/windows/devtools/index.ts
new file mode 100644
index 000000000..c08d0255d
--- /dev/null
+++ b/apps/stage-tamagotchi/src/main/windows/devtools/index.ts
@@ -0,0 +1,67 @@
+import { join, resolve } from 'node:path'
+
+import { BrowserWindow, shell } from 'electron'
+
+import icon from '../../../../resources/icon.png?asset'
+
+import { baseUrl, getElectronMainDirname, load, withHashRoute } from '../../libs/electron/location'
+import { createReusableWindow } from '../../libs/electron/window-manager'
+
+export interface DevtoolsWindowManager {
+  openWindow: (route?: string) => Promise<BrowserWindow>
+  getWindow: () => Promise<BrowserWindow>
+}
+
+export function setupDevtoolsWindow(): DevtoolsWindowManager {
+  const rendererBase = baseUrl(resolve(getElectronMainDirname(), '..', 'renderer'))
+  const defaultRoute = '/devtools/markdown-stress'
+  let currentRoute = defaultRoute
+
+  const reusable = createReusableWindow(async () => {
+    const window = new BrowserWindow({
+      title: 'Devtools',
+      width: 1020,
+      height: 720,
+      minWidth: 640,
+      minHeight: 480,
+      show: false,
+      icon,
+      webPreferences: {
+        preload: join(__dirname, '../preload/index.mjs'),
+        // Preload exposes Electron APIs and needs Node access.
+        sandbox: false,
+      },
+    })
+
+    window.on('ready-to-show', () => window.show())
+    window.webContents.setWindowOpenHandler((details) => {
+      shell.openExternal(details.url)
+      return { action: 'deny' }
+    })
+
+    await load(window, withHashRoute(rendererBase, currentRoute))
+    return window
+  })
+
+  async function openWindow(route?: string) {
+    if (route)
+      currentRoute = route
+
+    const window = await reusable.getWindow()
+    const targetRoute = route ?? currentRoute
+    const url = withHashRoute(rendererBase, targetRoute)
+
+    // If the route changes while the window is open, reload to that route.
+    const currentUrl = window.webContents.getURL()
+    if (!currentUrl.includes(`#${targetRoute}`)) {
+      await load(window, url)
+    }
+
+    return window
+  }
+
+  return {
+    openWindow,
+    getWindow: reusable.getWindow,
+  }
+}
diff --git a/apps/stage-tamagotchi/src/main/windows/settings/index.ts b/apps/stage-tamagotchi/src/main/windows/settings/index.ts
index 37da29805..485cdd256 100644
--- a/apps/stage-tamagotchi/src/main/windows/settings/index.ts
+++ b/apps/stage-tamagotchi/src/main/windows/settings/index.ts
@@ -1,4 +1,5 @@
 import type { AutoUpdater } from '../../services/electron/auto-updater'
+import type { DevtoolsWindowManager } from '../devtools'
 import type { WidgetsWindowManager } from '../widgets'
 
 import { join, resolve } from 'node:path'
@@ -14,6 +15,7 @@ import { setupSettingsWindowInvokes } from './rpc/index.electron'
 export function setupSettingsWindowReusableFunc(params: {
   widgetsManager: WidgetsWindowManager
   autoUpdater: AutoUpdater
+  devtoolsMarkdownStressWindow: DevtoolsWindowManager
   onWindowCreated?: (window: BrowserWindow) => void
 }) {
   return createReusableWindow(async () => {
@@ -40,7 +42,12 @@ export function setupSettingsWindowReusableFunc(params: {
     })
 
     await load(window, withHashRoute(baseUrl(resolve(getElectronMainDirname(), '..', 'renderer')), '/settings'))
-    await setupSettingsWindowInvokes({ settingsWindow: window, widgetsManager: params.widgetsManager, autoUpdater: params.autoUpdater })
+    await setupSettingsWindowInvokes({
+      settingsWindow: window,
+      widgetsManager: params.widgetsManager,
+      autoUpdater: params.autoUpdater,
+      devtoolsMarkdownStressWindow: params.devtoolsMarkdownStressWindow,
+    })
 
     return window
   }).getWindow
diff --git a/apps/stage-tamagotchi/src/main/windows/settings/rpc/index.electron.ts b/apps/stage-tamagotchi/src/main/windows/settings/rpc/index.electron.ts
index 5c087d7ee..5040e18a4 100644
--- a/apps/stage-tamagotchi/src/main/windows/settings/rpc/index.electron.ts
+++ b/apps/stage-tamagotchi/src/main/windows/settings/rpc/index.electron.ts
@@ -1,17 +1,23 @@
 import type { BrowserWindow } from 'electron'
 
 import type { AutoUpdater } from '../../../services/electron/auto-updater'
+import type { DevtoolsWindowManager } from '../../devtools'
 import type { WidgetsWindowManager } from '../../widgets'
 
 import { defineInvokeHandler } from '@moeru/eventa'
 import { createContext } from '@moeru/eventa/adapters/electron/main'
 import { ipcMain } from 'electron'
 
-import { electronOpenSettingsDevtools } from '../../../../shared/eventa'
+import { electronOpenDevtoolsWindow, electronOpenSettingsDevtools } from '../../../../shared/eventa'
 import { createWidgetsService } from '../../../services/airi/widgets'
 import { createAutoUpdaterService, createScreenService, createWindowService } from '../../../services/electron'
 
-export async function setupSettingsWindowInvokes(params: { settingsWindow: BrowserWindow, widgetsManager: WidgetsWindowManager, autoUpdater: AutoUpdater }) {
+export async function setupSettingsWindowInvokes(params: {
+  settingsWindow: BrowserWindow
+  widgetsManager: WidgetsWindowManager
+  autoUpdater: AutoUpdater
+  devtoolsMarkdownStressWindow: DevtoolsWindowManager
+}) {
   // TODO: once we refactored eventa to support window-namespaced contexts,
   // we can remove the setMaxListeners call below since eventa will be able to dispatch and
   // manage events within eventa's context system.
@@ -25,4 +31,7 @@ export async function setupSettingsWindowInvokes(params: { settingsWindow: Brows
   createAutoUpdaterService({ context, window: params.settingsWindow, service: params.autoUpdater })
 
   defineInvokeHandler(context, electronOpenSettingsDevtools, async () => params.settingsWindow.webContents.openDevTools({ mode: 'detach' }))
+  defineInvokeHandler(context, electronOpenDevtoolsWindow, async (payload) => {
+    await params.devtoolsMarkdownStressWindow.openWindow(payload?.route)
+  })
 }
diff --git a/apps/stage-tamagotchi/src/renderer/App.vue b/apps/stage-tamagotchi/src/renderer/App.vue
index 0d26d7ac1..8afbe66d6 100644
--- a/apps/stage-tamagotchi/src/renderer/App.vue
+++ b/apps/stage-tamagotchi/src/renderer/App.vue
@@ -8,6 +8,7 @@ import { useModsServerChannelStore } from '@proj-airi/stage-ui/stores/mods/api/c
 import { useContextBridgeStore } from '@proj-airi/stage-ui/stores/mods/api/context-bridge'
 import { useAiriCardStore } from '@proj-airi/stage-ui/stores/modules/airi-card'
 import { useOnboardingStore } from '@proj-airi/stage-ui/stores/onboarding'
+import { usePerfTracerBridgeStore } from '@proj-airi/stage-ui/stores/perf-tracer-bridge'
 import { useSettings } from '@proj-airi/stage-ui/stores/settings'
 import { useTheme } from '@proj-airi/ui'
 import { storeToRefs } from 'pinia'
@@ -31,6 +32,7 @@ const cardStore = useAiriCardStore()
 const serverChannelStore = useModsServerChannelStore()
 const characterOrchestratorStore = useCharacterOrchestratorStore()
 const analyticsStore = useSharedAnalyticsStore()
+usePerfTracerBridgeStore()
 
 watch(language, () => {
   i18n.locale.value = language.value
diff --git a/apps/stage-tamagotchi/src/renderer/layouts/settings.vue b/apps/stage-tamagotchi/src/renderer/layouts/settings.vue
index 81d49b1a2..60889ae05 100644
--- a/apps/stage-tamagotchi/src/renderer/layouts/settings.vue
+++ b/apps/stage-tamagotchi/src/renderer/layouts/settings.vue
@@ -120,6 +120,10 @@ const routeHeaderMetadataMap = computed(() => {
       subtitle: t('tamagotchi.settings.devtools.title'),
       title: t('tamagotchi.settings.devtools.pages.widgets-calling.title'),
     },
+    '/devtools/markdown-stress': {
+      subtitle: t('tamagotchi.settings.devtools.title'),
+      title: t('tamagotchi.settings.devtools.pages.markdown-stress.title'),
+    },
     '/devtools/context-flow': {
       subtitle: t('tamagotchi.settings.devtools.title'),
       title: t('tamagotchi.settings.devtools.pages.context-flow.title'),
diff --git a/apps/stage-tamagotchi/src/renderer/pages/devtools/lag-visualizer.vue b/apps/stage-tamagotchi/src/renderer/pages/devtools/lag-visualizer.vue
new file mode 100644
index 000000000..284507e54
--- /dev/null
+++ b/apps/stage-tamagotchi/src/renderer/pages/devtools/lag-visualizer.vue
@@ -0,0 +1,24 @@
+<script setup lang="ts">
+// NOTICE: This view is defined for parity but not used by stage-tamagotchi yet.
+import { useI18n } from 'vue-i18n'
+
+// TODO: Desktop lag overlay/parity with web implementation.
+const { t } = useI18n()
+</script>
+
+<template>
+  <div flex="~ col gap-3" pb-6>
+    <div text="lg neutral-100">
+      {{ t('tamagotchi.settings.devtools.pages.performance-visualizer.title') }}
+    </div>
+    <div text="sm neutral-400" flex="~ col gap-1">
+      <span>{{ t('tamagotchi.settings.devtools.pages.performance-visualizer.description') }}</span>
+      <span>{{ t('settings.wip.description') }}</span>
+    </div>
+  </div>
+</template>
+
+<route lang="yaml">
+meta:
+  layout: settings
+</route>
diff --git a/apps/stage-tamagotchi/src/renderer/pages/settings/system/developer.vue b/apps/stage-tamagotchi/src/renderer/pages/settings/system/developer.vue
index 7ad82a6ec..207ad0f2f 100644
--- a/apps/stage-tamagotchi/src/renderer/pages/settings/system/developer.vue
+++ b/apps/stage-tamagotchi/src/renderer/pages/settings/system/developer.vue
@@ -4,7 +4,7 @@ import { useSettings } from '@proj-airi/stage-ui/stores/settings'
 import { computed } from 'vue'
 import { useI18n } from 'vue-i18n'
 
-import { electronOpenMainDevtools } from '../../../../shared/eventa'
+import { electronOpenDevtoolsWindow, electronOpenMainDevtools } from '../../../../shared/eventa'
 import { useElectronEventaInvoke } from '../../../composables/electron-vueuse'
 
 const { t } = useI18n()
@@ -62,6 +62,7 @@ const menu = computed(() => [
 ])
 
 const openDevTools = useElectronEventaInvoke(electronOpenMainDevtools)
+const openMarkdownStressWindow = useElectronEventaInvoke(electronOpenDevtoolsWindow)
 </script>
 
 <template>
@@ -80,6 +81,20 @@ const openDevTools = useElectronEventaInvoke(electronOpenMainDevtools)
   >
     {{ t('settings.pages.page.developers.open-devtools.button') }}
   </ButtonBar>
+  <ButtonBar
+    v-motion
+    mb-2
+    icon="i-solar:code-bold-duotone"
+    :text="t('tamagotchi.settings.devtools.pages.markdown-stress.title')"
+    :initial="{ opacity: 0, y: 10 }"
+    :enter="{ opacity: 1, y: 0 }"
+    :duration="250 + (19 * 10)"
+    :delay="2 * 50"
+    transition="all ease-in-out duration-250"
+    @click="() => openMarkdownStressWindow({ route: '/devtools/markdown-stress' })"
+  >
+    {{ t('tamagotchi.settings.devtools.pages.markdown-stress.title') }}
+  </ButtonBar>
   <CheckBar
     v-model="settings.disableTransitions"
     v-motion
@@ -90,7 +105,7 @@ const openDevTools = useElectronEventaInvoke(electronOpenMainDevtools)
     :initial="{ opacity: 0, y: 10 }"
     :enter="{ opacity: 1, y: 0 }"
     :duration="250 + (19 * 10)"
-    :delay="2 * 50"
+    :delay="3 * 50"
     transition="all ease-in-out duration-250"
   />
   <CheckBar
@@ -104,7 +119,7 @@ const openDevTools = useElectronEventaInvoke(electronOpenMainDevtools)
     :initial="{ opacity: 0, y: 10 }"
     :enter="{ opacity: 1, y: 0 }"
     :duration="250 + (20 * 10)"
-    :delay="3 * 50"
+    :delay="4 * 50"
     transition="all ease-in-out duration-250"
   />
 
diff --git a/apps/stage-tamagotchi/src/shared/eventa.ts b/apps/stage-tamagotchi/src/shared/eventa.ts
index da65407e4..c170aef78 100644
--- a/apps/stage-tamagotchi/src/shared/eventa.ts
+++ b/apps/stage-tamagotchi/src/shared/eventa.ts
@@ -6,6 +6,7 @@ export const electronOpenMainDevtools = defineInvokeEventa('eventa:invoke:electr
 export const electronOpenSettings = defineInvokeEventa('eventa:invoke:electron:windows:settings:open')
 export const electronOpenChat = defineInvokeEventa('eventa:invoke:electron:windows:chat:open')
 export const electronOpenSettingsDevtools = defineInvokeEventa('eventa:invoke:electron:windows:settings:devtools:open')
+export const electronOpenDevtoolsWindow = defineInvokeEventa<void, { route?: string }>('eventa:invoke:electron:windows:devtools:open')
 export const captionIsFollowingWindowChanged = defineEventa<boolean>('eventa:event:electron:windows:caption-overlay:is-following-window-changed')
 export const captionGetIsFollowingWindow = defineInvokeEventa<boolean>('eventa:invoke:electron:windows:caption-overlay:get-is-following-window')
 
diff --git a/apps/stage-web/package.json b/apps/stage-web/package.json
index 1e8e22b61..f09e33581 100644
--- a/apps/stage-web/package.json
+++ b/apps/stage-web/package.json
@@ -31,6 +31,7 @@
     "@proj-airi/model-driver-mediapipe": "workspace:^",
     "@proj-airi/server-sdk": "workspace:^",
     "@proj-airi/stage-layouts": "workspace:^",
+    "@proj-airi/stage-shared": "workspace:^",
     "@proj-airi/stage-ui": "workspace:^",
     "@proj-airi/stage-ui-three": "workspace:^",
     "@proj-airi/stage-ui-three-performance-runtime": "workspace:^",
diff --git a/apps/stage-web/src/App.vue b/apps/stage-web/src/App.vue
index 708b27815..ccdb39f9d 100644
--- a/apps/stage-web/src/App.vue
+++ b/apps/stage-web/src/App.vue
@@ -16,6 +16,8 @@ import { useI18n } from 'vue-i18n'
 import { RouterView } from 'vue-router'
 import { toast, Toaster } from 'vue-sonner'
 
+import PerformanceOverlay from './components/Devtools/PerformanceOverlay.vue'
+
 import { usePWAStore } from './stores/pwa'
 
 import 'vue-sonner/style.css'
@@ -125,6 +127,8 @@ function handleSetupSkipped() {
     @configured="handleSetupConfigured"
     @skipped="handleSetupSkipped"
   />
+
+  <PerformanceOverlay />
 </template>
 
 <style>
diff --git a/apps/stage-web/src/components/Devtools/PerformanceOverlay.vue b/apps/stage-web/src/components/Devtools/PerformanceOverlay.vue
new file mode 100644
index 000000000..39783683e
--- /dev/null
+++ b/apps/stage-web/src/components/Devtools/PerformanceOverlay.vue
@@ -0,0 +1,127 @@
+<script setup lang="ts">
+import type { LagMetric } from '../../stores/devtools-lag'
+
+import { storeToRefs } from 'pinia'
+import { computed, ref } from 'vue'
+
+import { useDevtoolsLagStore } from '../../stores/devtools-lag'
+
+const store = useDevtoolsLagStore()
+const { enabled, buffers, recording } = storeToRefs(store)
+
+const hovered = ref(false)
+
+const metrics: Array<{ key: LagMetric, label: string, enabled: () => boolean }> = [
+  { key: 'fps', label: 'FPS', enabled: () => enabled.value.fps },
+  { key: 'frameDuration', label: 'Frame (ms)', enabled: () => enabled.value.frameDuration },
+  { key: 'longtask', label: 'Long task (ms)', enabled: () => enabled.value.longtask },
+  { key: 'memory', label: 'Memory (MB)', enabled: () => enabled.value.memory },
+]
+
+const visibleMetrics = computed(() => metrics.filter(metric => metric.enabled()))
+const hasAnyEnabled = computed(() => visibleMetrics.value.length > 0)
+const metricStatsMap = computed<Record<LagMetric, ReturnType<typeof store.calcStats>>>(() => {
+  const result = {} as Record<LagMetric, ReturnType<typeof store.calcStats>>
+  for (const metric of metrics) {
+    const values = buffers.value[metric.key].map(sample => sample.value)
+    result[metric.key] = store.calcStats(values)
+  }
+  return result
+})
+const metricsWithStats = computed(() => visibleMetrics.value.map(metric => ({
+  ...metric,
+  stats: metricStatsMap.value[metric.key],
+})))
+
+function formatValue(metric: string, value: number) {
+  if (!Number.isFinite(value))
+    return '--'
+
+  if (metric === 'memory')
+    return `${(value / 1048576).toFixed(1)}`
+
+  if (metric === 'fps')
+    return value.toFixed(0)
+
+  return value.toFixed(1)
+}
+
+function barSeries(metric: LagMetric) {
+  const values = buffers.value[metric].map(sample => sample.value)
+  const histogram = store.buildHistogram(values, 20)
+  const max = Math.max(1, ...histogram.map(bin => bin.count))
+  return histogram.map(bin => ({
+    width: `${100 / (histogram.length || 1)}%`,
+    height: `${(bin.count / max) * 100}%`,
+  }))
+}
+
+function toggleRecording() {
+  if (recording.value) {
+    const snapshot = store.stopRecording()
+    if (snapshot)
+      store.exportCsv(snapshot)
+    return
+  }
+
+  store.startRecording()
+}
+</script>
+
+<template>
+  <div
+    v-if="hasAnyEnabled"
+    :style="{ opacity: hovered ? 1 : 0.3 }"
+    class="fixed bottom-3 left-3 z-50"
+    p-3
+    flex="~ col gap-2"
+    rounded="xl"
+    bg="neutral-900/80"
+    text="white sm"
+    shadow="xl"
+    transition="opacity 200ms ease"
+    @mouseenter="hovered = true"
+    @mouseleave="hovered = false"
+  >
+    <div flex="~ row items-center gap-2" justify-between>
+      <div text="xs neutral-200" uppercase tracking="wide">
+        Performance Overlay
+      </div>
+      <button
+        type="button"
+        class="inline-flex items-center gap-1 rounded bg-white/10 px-2 py-1 text-xs transition-colors hover:bg-white/20"
+        @click="toggleRecording"
+      >
+        <span
+          class="inline-block h-2 w-2 rounded-full"
+          :class="recording ? 'bg-red-400' : 'bg-neutral-400'"
+        />
+        <span>{{ recording ? 'Stop' : 'Record' }}</span>
+      </button>
+    </div>
+
+    <div v-for="metric in metricsWithStats" :key="metric.key" flex="~ col gap-1">
+      <div flex="~ row items-center justify-between">
+        <span text="xs neutral-100">{{ metric.label }}</span>
+        <span text="xs neutral-300">
+          <template v-if="metric.stats.latest">
+            avg {{ formatValue(metric.key, metric.stats.avg) }}
+            /
+            p95 {{ formatValue(metric.key, metric.stats.p95) }}
+          </template>
+          <template v-else>
+            --
+          </template>
+        </span>
+      </div>
+      <div class="h-10 flex items-end gap-0.5 overflow-hidden rounded bg-white/5 px-1 py-1">
+        <div
+          v-for="(bar, index) in barSeries(metric.key)"
+          :key="index"
+          :style="{ width: bar.width, height: bar.height }"
+          class="bg-white/50"
+        />
+      </div>
+    </div>
+  </div>
+</template>
diff --git a/apps/stage-web/src/composables/perf/register-lag-sampler.ts b/apps/stage-web/src/composables/perf/register-lag-sampler.ts
new file mode 100644
index 000000000..092316909
--- /dev/null
+++ b/apps/stage-web/src/composables/perf/register-lag-sampler.ts
@@ -0,0 +1,128 @@
+import type { PerfTracer } from '@proj-airi/stage-shared'
+
+interface LagEnabled {
+  fps: boolean
+  frameDuration: boolean
+  longtask: boolean
+  memory: boolean
+}
+
+export function createLagSampler(tracer: PerfTracer) {
+  let rafId: number | undefined
+  let lastTs: number | undefined
+  let longTaskObserver: PerformanceObserver | undefined
+  let memoryTimer: ReturnType<typeof setInterval> | undefined
+
+  function stopRaf() {
+    if (rafId !== undefined) {
+      cancelAnimationFrame(rafId)
+      rafId = undefined
+    }
+    lastTs = undefined
+  }
+
+  function startRaf() {
+    stopRaf()
+
+    const loop = (ts: number) => {
+      if (lastTs !== undefined) {
+        const delta = ts - lastTs
+        const fps = delta > 0 ? 1000 / delta : 0
+
+        tracer.emit({
+          tracerId: 'lag',
+          name: 'fps',
+          ts,
+          duration: fps,
+        })
+
+        tracer.emit({
+          tracerId: 'lag',
+          name: 'frameDuration',
+          ts,
+          duration: delta,
+        })
+      }
+
+      lastTs = ts
+      rafId = requestAnimationFrame(loop)
+    }
+
+    rafId = requestAnimationFrame(loop)
+  }
+
+  function stopLongTaskObserver() {
+    longTaskObserver?.disconnect()
+    longTaskObserver = undefined
+  }
+
+  function startLongTaskObserver() {
+    stopLongTaskObserver()
+    if (!('PerformanceObserver' in window))
+      return
+
+    try {
+      longTaskObserver = new PerformanceObserver((list) => {
+        for (const entry of list.getEntries()) {
+          tracer.emit({
+            tracerId: 'lag',
+            name: 'longtask',
+            ts: entry.startTime,
+            duration: entry.duration,
+          })
+        }
+      })
+      longTaskObserver.observe({ type: 'longtask', buffered: true })
+    }
+    catch (error) {
+      console.warn('[LagSampler] Failed to start longtask observer', error)
+    }
+  }
+
+  function stopMemoryTimer() {
+    if (memoryTimer) {
+      clearInterval(memoryTimer)
+      memoryTimer = undefined
+    }
+  }
+
+  function startMemoryTimer() {
+    stopMemoryTimer()
+    const perfWithMemory = performance as Performance & { memory?: { usedJSHeapSize: number } }
+    if (!perfWithMemory.memory)
+      return
+
+    memoryTimer = setInterval(() => {
+      tracer.emit({
+        tracerId: 'lag',
+        name: 'memory',
+        ts: performance.now(),
+        duration: perfWithMemory.memory?.usedJSHeapSize ?? 0,
+      })
+    }, 1000)
+  }
+
+  function start(enabled: LagEnabled) {
+    stop()
+
+    if (enabled.fps || enabled.frameDuration)
+      startRaf()
+
+    if (enabled.longtask)
+      startLongTaskObserver()
+
+    if (enabled.memory)
+      startMemoryTimer()
+  }
+
+  function stop() {
+    stopRaf()
+    stopLongTaskObserver()
+    stopMemoryTimer()
+  }
+
+  return {
+    start,
+    stop,
+  }
+}
diff --git a/apps/stage-web/src/pages/devtools/performance-visualizer.vue b/apps/stage-web/src/pages/devtools/performance-visualizer.vue
new file mode 100644
index 000000000..0da779aff
--- /dev/null
+++ b/apps/stage-web/src/pages/devtools/performance-visualizer.vue
@@ -0,0 +1,116 @@
+<script setup lang="ts">
+import { ButtonBar, CheckBar } from '@proj-airi/stage-ui/components'
+import { useMagicKeys, whenever } from '@vueuse/core'
+import { storeToRefs } from 'pinia'
+import { computed } from 'vue'
+
+import { useDevtoolsLagStore } from '../../stores/devtools-lag'
+
+const lagStore = useDevtoolsLagStore()
+const { enabled, lastRecording, recording } = storeToRefs(lagStore)
+
+const recordingLabel = computed(() => recording.value ? 'Stop recording (max 60s)' : 'Start recording')
+const hasRecording = computed(() => !!lastRecording.value)
+const allEnabled = computed(() => enabled.value.fps && enabled.value.frameDuration && enabled.value.longtask && enabled.value.memory)
+
+const magicKeys = useMagicKeys()
+whenever(magicKeys['ctrl+alt+l'], () => toggleAll(true))
+whenever(magicKeys['ctrl+alt+k'], () => toggleAll(false))
+
+function toggleAll(on: boolean) {
+  lagStore.toggleAll(on)
+}
+
+function exportCsv() {
+  lagStore.exportCsv()
+}
+</script>
+
+<template>
+  <div flex="~ col gap-4" pb-6>
+    <div flex="~ col gap-2">
+      <div flex="~ row items-center gap-2">
+        <CheckBar
+          :model-value="allEnabled"
+          icon-on="i-solar:sledgehammer-bold-duotone"
+          icon-off="i-solar:sledgehammer-bold-duotone"
+          text="Enable all metrics"
+          description="Toggle all lag metrics (FPS, frame time, long task, memory)"
+          @update:model-value="value => toggleAll(Boolean(value))"
+        />
+        <ButtonBar
+          :icon="recording ? 'i-solar:stop-circle-bold-duotone' : 'i-solar:recive-bold-duotone'"
+          text="Recording"
+          @click="recording ? lagStore.stopRecording() : lagStore.startRecording()"
+        >
+          {{ recordingLabel }}
+        </ButtonBar>
+        <ButtonBar
+          icon="i-solar:export-bold-duotone"
+          text="Export CSV"
+          :disabled="!hasRecording"
+          @click="exportCsv"
+        >
+          Export last recording
+        </ButtonBar>
+      </div>
+
+      <div flex="~ col gap-2">
+        <CheckBar
+          v-model="enabled.fps"
+          icon-on="i-solar:activity-bold-duotone"
+          icon-off="i-solar:activity-bold-duotone"
+          text="FPS"
+          description="Collect FPS histogram"
+        />
+        <CheckBar
+          v-model="enabled.frameDuration"
+          icon-on="i-solar:chart-bold-duotone"
+          icon-off="i-solar:chart-bold-duotone"
+          text="Frame time (ms)"
+          description="Collect frame duration histogram"
+        />
+        <CheckBar
+          v-model="enabled.longtask"
+          icon-on="i-solar:timer-bold-duotone"
+          icon-off="i-solar:timer-bold-duotone"
+          text="Long tasks"
+          description="PerformanceObserver('longtask')"
+        />
+        <CheckBar
+          v-model="enabled.memory"
+          icon-on="i-solar:database-bold-duotone"
+          icon-off="i-solar:database-bold-duotone"
+          text="Memory"
+          description="Sample performance.memory every second"
+        />
+      </div>
+    </div>
+
+    <div v-if="hasRecording" flex="~ col gap-2" rounded="lg" border="1 dashed neutral-700" p-3>
+      <div text="sm neutral-200">
+        Last recording
+      </div>
+      <div text="xs neutral-400">
+        Started at {{ lastRecording?.startedAt.toFixed(0) }} ms, duration
+        {{ (lastRecording!.stoppedAt - lastRecording!.startedAt).toFixed(0) }} ms
+      </div>
+      <div text="xs neutral-400">
+        Samples:
+        FPS {{ lastRecording?.samples.fps.length }},
+        Frames {{ lastRecording?.samples.frameDuration.length }},
+        Long tasks {{ lastRecording?.samples.longtask.length }},
+        Memory {{ lastRecording?.samples.memory.length }}
+      </div>
+    </div>
+
+    <div text="xs neutral-500">
+      Overlay is visible when any metric is enabled. Recording caps at 60s.
+    </div>
+  </div>
+</template>
+
+<route lang="yaml">
+meta:
+  layout: settings
+</route>
diff --git a/apps/stage-web/src/pages/settings/system/developer.vue b/apps/stage-web/src/pages/settings/system/developer.vue
index adf8109af..911e7c6e2 100644
--- a/apps/stage-web/src/pages/settings/system/developer.vue
+++ b/apps/stage-web/src/pages/settings/system/developer.vue
@@ -14,6 +14,18 @@ const menu = computed(() => [
     icon: 'i-solar:sledgehammer-bold-duotone',
     to: '/devtools/audio-record',
   },
+  {
+    title: t('settings.pages.system.sections.section.developer.sections.section.performance-visualizer.title'),
+    description: t('settings.pages.system.sections.section.developer.sections.section.performance-visualizer.description'),
+    icon: 'i-solar:sledgehammer-bold-duotone',
+    to: '/devtools/performance-visualizer',
+  },
+  {
+    title: t('settings.pages.system.sections.section.developer.sections.section.markdown-stress.title'),
+    description: t('settings.pages.system.sections.section.developer.sections.section.markdown-stress.description'),
+    icon: 'i-solar:sledgehammer-bold-duotone',
+    to: '/devtools/markdown-stress',
+  },
   {
     title: 'Background Theme color blending',
     description: 'Test blending & theme',
diff --git a/apps/stage-web/src/stores/devtools-lag.ts b/apps/stage-web/src/stores/devtools-lag.ts
new file mode 100644
index 000000000..8cda1733b
--- /dev/null
+++ b/apps/stage-web/src/stores/devtools-lag.ts
@@ -0,0 +1,273 @@
+import type { TraceEvent } from '@proj-airi/stage-shared'
+
+import { defaultPerfTracer, exportCsv as exportCsvFile } from '@proj-airi/stage-shared'
+import { defineStore } from 'pinia'
+import { reactive, ref, watch } from 'vue'
+
+import { createLagSampler } from '../composables/perf/register-lag-sampler'
+
+export type LagMetric = 'fps' | 'frameDuration' | 'longtask' | 'memory'
+
+interface Sample {
+  ts: number
+  value: number
+  meta?: Record<string, any>
+}
+
+interface RecordingSnapshot {
+  startedAt: number
+  stoppedAt: number
+  samples: Record<LagMetric, Sample[]>
+}
+
+interface HistogramBin {
+  start: number
+  end: number
+  count: number
+}
+
+function createEmptySamples(): Record<LagMetric, Sample[]> {
+  return {
+    fps: [],
+    frameDuration: [],
+    longtask: [],
+    memory: [],
+  }
+}
+
+function pruneSamples(buffer: Sample[], cutoffTs: number) {
+  while (buffer.length && buffer[0].ts < cutoffTs)
+    buffer.shift()
+}
+
+function calcStats(values: number[]) {
+  if (!values.length)
+    return { avg: 0, p95: 0, latest: 0 }
+
+  const total = values.reduce((acc, n) => acc + n, 0)
+  const avg = total / values.length
+  const sorted = [...values].sort((a, b) => a - b)
+  const idx = Math.max(0, Math.floor(0.95 * (sorted.length - 1)))
+  const p95 = sorted[idx]
+  const latest = values[values.length - 1]
+
+  return { avg, p95, latest }
+}
+
+function buildHistogram(values: number[], bins = 20): HistogramBin[] {
+  if (!values.length)
+    return []
+
+  const min = Math.min(...values)
+  const max = Math.max(...values)
+  if (min === max) {
+    return [{
+      start: min,
+      end: max || min + 1,
+      count: values.length,
+    }]
+  }
+
+  const width = (max - min) / bins
+  const buckets = Array.from({ length: bins }, (_, idx) => ({
+    start: min + (idx * width),
+    end: min + ((idx + 1) * width),
+    count: 0,
+  }))
+
+  for (const value of values) {
+    let binIndex = Math.floor((value - min) / width)
+    if (binIndex >= bins)
+      binIndex = bins - 1
+
+    buckets[binIndex].count += 1
+  }
+
+  return buckets
+}
+
+export const useDevtoolsLagStore = defineStore('devtoolsLag', () => {
+  const enabled = reactive({
+    fps: false,
+    frameDuration: false,
+    longtask: false,
+    memory: false,
+  })
+
+  const windowMs = 10000
+  const buffers = reactive(createEmptySamples())
+
+  const recording = ref(false)
+  const recordingStartedAt = ref<number | null>(null)
+  const recordingSamples = reactive(createEmptySamples())
+  const lastRecording = ref<RecordingSnapshot>()
+  let recordingTimeout: ReturnType<typeof setTimeout> | undefined
+
+  const sampler = createLagSampler(defaultPerfTracer)
+  let unsubscribeTracer: (() => void) | undefined
+  let releaseTracer: (() => void) | undefined
+
+  function resetRecordingSamples() {
+    for (const metric of Object.keys(recordingSamples) as LagMetric[])
+      recordingSamples[metric] = []
+  }
+
+  function applySample(metric: LagMetric, value: number, meta?: Record<string, any>) {
+    const ts = performance.now()
+    const cutoff = ts - windowMs
+
+    const buffer = buffers[metric]
+    buffer.push({ ts, value, meta })
+    pruneSamples(buffer, cutoff)
+
+    if (recording.value) {
+      const sampleBuffer = recordingSamples[metric]
+      sampleBuffer.push({ ts, value, meta })
+    }
+  }
+
+  function startRecording() {
+    if (recording.value)
+      return
+
+    recording.value = true
+    recordingStartedAt.value = performance.now()
+    resetRecordingSamples()
+
+    recordingTimeout = setTimeout(() => stopRecording(), 60000)
+  }
+
+  function stopRecording(): RecordingSnapshot | undefined {
+    if (!recording.value)
+      return
+
+    if (recordingTimeout) {
+      clearTimeout(recordingTimeout)
+      recordingTimeout = undefined
+    }
+
+    const stoppedAt = performance.now()
+    const snapshot: RecordingSnapshot = {
+      startedAt: recordingStartedAt.value || stoppedAt,
+      stoppedAt,
+      samples: {
+        fps: [...recordingSamples.fps],
+        frameDuration: [...recordingSamples.frameDuration],
+        longtask: [...recordingSamples.longtask],
+        memory: [...recordingSamples.memory],
+      },
+    }
+    lastRecording.value = snapshot
+
+    resetRecordingSamples()
+    recordingStartedAt.value = null
+    recording.value = false
+    return snapshot
+  }
+
+  function stopAll() {
+    sampler.stop()
+    if (unsubscribeTracer) {
+      unsubscribeTracer()
+      unsubscribeTracer = undefined
+    }
+    releaseTracer?.()
+    releaseTracer = undefined
+  }
+
+  function ensureSampler() {
+    const anyEnabled = enabled.fps || enabled.frameDuration || enabled.longtask || enabled.memory
+    if (!anyEnabled) {
+      stopAll()
+      return
+    }
+
+    // Start tracer listener if needed
+    if (!unsubscribeTracer) {
+      unsubscribeTracer = defaultPerfTracer.subscribe((event: TraceEvent) => {
+        if (event.tracerId !== 'lag')
+          return
+
+        const metric = event.name as LagMetric
+        if (!['fps', 'frameDuration', 'longtask', 'memory'].includes(metric))
+          return
+
+        // Only accept samples for enabled metrics
+        const isMetricEnabled = enabled[metric]
+
+        if (!isMetricEnabled)
+          return
+
+        const value = typeof event.duration === 'number' ? event.duration : 0
+        applySample(metric, value, event.meta)
+      })
+    }
+
+    if (!releaseTracer)
+      releaseTracer = defaultPerfTracer.acquire('lag-overlay')
+    sampler.start({
+      fps: enabled.fps,
+      frameDuration: enabled.frameDuration,
+      longtask: enabled.longtask,
+      memory: enabled.memory,
+    })
+  }
+
+  function toggleAll(on: boolean) {
+    enabled.fps = on
+    enabled.frameDuration = on
+    enabled.longtask = on
+    enabled.memory = on
+    ensureSampler()
+  }
+
+  function exportCsv(snapshot?: RecordingSnapshot) {
+    const target = snapshot ?? lastRecording.value
+    if (!target)
+      return
+
+    const rows: Array<Array<string | number>> = [['metric', 'ts', 'value', 'meta']]
+    for (const metric of Object.keys(target.samples) as LagMetric[]) {
+      for (const sample of target.samples[metric]) {
+        rows.push([
+          metric,
+          sample.ts.toFixed(3),
+          sample.value,
+          JSON.stringify(sample.meta ?? {}),
+        ])
+      }
+    }
+
+    exportCsvFile(rows, 'lag-recording')
+  }
+
+  // React to enablement changes
+  watch(
+    () => ({ ...enabled }),
+    () => {
+      ensureSampler()
+    },
+    { deep: true },
+  )
+
+  // Cleanup on tab close
+  if (typeof window !== 'undefined') {
+    window.addEventListener('beforeunload', () => {
+      stopRecording()
+      stopAll()
+    })
+  }
+
+  return {
+    enabled,
+    buffers,
+    recording,
+    lastRecording,
+    startRecording,
+    stopRecording,
+    exportCsv,
+    toggleAll,
+    calcStats,
+    buildHistogram,
+  }
+})
diff --git a/packages/i18n/src/locales/en/settings.yaml b/packages/i18n/src/locales/en/settings.yaml
index c343e97a5..5cd1bdf4c 100644
--- a/packages/i18n/src/locales/en/settings.yaml
+++ b/packages/i18n/src/locales/en/settings.yaml
@@ -738,6 +738,12 @@ pages:
           title: Developer
           sections:
             section:
+              performance-visualizer:
+                title: Performance Visualizer
+                description: Toggle FPS/long task/memory overlay
+              markdown-stress:
+                title: Markdown Stress
+                description: Stress markdown parsing and rendering with heavy chat payloads
               use-magic-keys:
                 title: useMagicKeys
                 description: Test shortcuts
diff --git a/packages/i18n/src/locales/en/tamagotchi/settings.yaml b/packages/i18n/src/locales/en/tamagotchi/settings.yaml
index 6e5fbe1e0..0b74ec541 100644
--- a/packages/i18n/src/locales/en/tamagotchi/settings.yaml
+++ b/packages/i18n/src/locales/en/tamagotchi/settings.yaml
@@ -32,5 +32,13 @@ devtools:
   pages:
     context-flow:
       title: Context Flow
+    lag-visualizer:
+      title: Lag Visualizer
+    performance-visualizer:
+      title: Performance Visualizer
+      description: Toggle FPS/long task/memory overlay
+    markdown-stress:
+      title: Markdown Stress
+      description: Stress markdown parsing and rendering with heavy chat payloads
     widgets-calling:
       title: Widget Calling
diff --git a/packages/stage-layouts/src/layouts/settings.vue b/packages/stage-layouts/src/layouts/settings.vue
index d406f2212..d3edb6903 100644
--- a/packages/stage-layouts/src/layouts/settings.vue
+++ b/packages/stage-layouts/src/layouts/settings.vue
@@ -114,6 +114,14 @@ const routeHeaderMetadataMap = computed(() => {
       subtitle: t('tamagotchi.settings.devtools.title'),
       title: t('tamagotchi.settings.devtools.pages.context-flow.title'),
     },
+    '/devtools/performance-visualizer': {
+      subtitle: t('settings.title'),
+      title: t('settings.pages.system.sections.section.developer.sections.section.performance-visualizer.title'),
+    },
+    '/devtools/markdown-stress': {
+      subtitle: t('settings.title'),
+      title: t('settings.pages.system.sections.section.developer.sections.section.markdown-stress.title'),
+    },
   }
 
   for (const metadata of allProvidersMetadata.value) {
diff --git a/packages/stage-pages/src/pages/devtools/markdown-stress.vue b/packages/stage-pages/src/pages/devtools/markdown-stress.vue
new file mode 100644
index 000000000..9ba5074a5
--- /dev/null
+++ b/packages/stage-pages/src/pages/devtools/markdown-stress.vue
@@ -0,0 +1,159 @@
+<script setup lang="ts">
+import { ButtonBar, Callout, Section } from '@proj-airi/stage-ui/components'
+import { useMarkdownStressStore } from '@proj-airi/stage-ui/stores/markdown-stress'
+import { storeToRefs } from 'pinia'
+import { computed } from 'vue'
+import { useI18n } from 'vue-i18n'
+
+const stressStore = useMarkdownStressStore()
+const { t } = useI18n()
+const { capturing, events, isMock, lastRun, payloadPreview, scheduleDelayMs, runState } = storeToRefs(stressStore)
+
+const previewText = computed(() => payloadPreview.value ?? '')
+const lastRunSummary = computed(() => {
+  if (!lastRun.value)
+    return undefined
+
+  return {
+    events: lastRun.value.events.length,
+    durationMs: (lastRun.value.stoppedAt - lastRun.value.startedAt).toFixed(0),
+  }
+})
+const runSummary = computed(() => {
+  return `Run: ${runState.value}, capturing: ${capturing.value ? 'yes' : 'no'}, events: ${events.value.length}`
+})
+
+function toggleCapture() {
+  if (capturing.value)
+    stressStore.stopCapture()
+  else
+    stressStore.startCapture()
+}
+
+function toggleMode() {
+  stressStore.toggleMockMode()
+}
+</script>
+
+<template>
+  <div class="grid gap-4 p-4 lg:grid-cols-[1.5fr_1fr]">
+    <Section
+      :title="t('settings.pages.system.sections.section.developer.sections.section.markdown-stress.title')"
+      :description="t('settings.pages.system.sections.section.developer.sections.section.markdown-stress.description')"
+      icon="i-solar:code-circle-bold-duotone"
+      inner-class="gap-4"
+    >
+      <div class="flex flex-wrap gap-2">
+        <ButtonBar
+          class="w-full sm:w-auto"
+          icon="i-solar:magic-stick-bold-duotone"
+          text="Preview"
+          @click="stressStore.generatePreview()"
+        >
+          Generate payload preview
+        </ButtonBar>
+        <ButtonBar
+          class="w-full sm:w-auto"
+          icon="i-solar:play-circle-bold-duotone"
+          :text="runState === 'running' ? 'Abort run' : runState === 'scheduled' ? 'Unschedule' : 'Replay'"
+          :disabled="!isMock && !stressStore.canRunOnline"
+          @click="stressStore.scheduleRun()"
+        >
+          {{ runState === 'running' ? 'Abort now' : runState === 'scheduled' ? 'Cancel replay' : 'Replay to provider' }}
+        </ButtonBar>
+        <ButtonBar
+          class="w-full sm:w-auto"
+          :icon="capturing ? 'i-solar:stop-circle-bold-duotone' : 'i-solar:recive-bold-duotone'"
+          text="Capture"
+          @click="toggleCapture"
+        >
+          {{ capturing ? 'Stop capture' : 'Start capture' }}
+        </ButtonBar>
+        <ButtonBar
+          class="w-full sm:w-auto"
+          icon="i-solar:export-bold-duotone"
+          text="Export"
+          :disabled="!lastRun?.events.length"
+          @click="stressStore.exportCsv()"
+        >
+          Export last run
+        </ButtonBar>
+        <ButtonBar
+          class="w-full sm:w-auto"
+          :icon="isMock ? 'i-solar:simplerockets-bold-duotone' : 'i-solar:cloud-bold-duotone'"
+          :text="isMock ? 'Mode: Mock' : 'Mode: Live'"
+          @click="toggleMode"
+        >
+          {{ isMock ? 'Switch to live provider' : 'Switch to mock stream' }}
+        </ButtonBar>
+      </div>
+
+      <div class="grid gap-3 md:grid-cols-[auto_1fr] md:items-center">
+        <label class="text-xs text-neutral-400">Schedule delay (ms)</label>
+        <input
+          v-model.number="scheduleDelayMs"
+          type="number"
+          min="0"
+          class="max-w-[180px] w-full border border-neutral-700 rounded bg-neutral-900 px-2 py-1 text-sm text-neutral-100"
+        >
+      </div>
+
+      <Callout label="Run state" theme="violet">
+        <div class="text-xs text-neutral-200">
+          {{ runSummary }}
+        </div>
+        <div class="text-xs text-neutral-500">
+          Capture to record recent events; export last run for offline review.
+        </div>
+      </Callout>
+
+      <Callout v-if="lastRunSummary" label="Last run" theme="orange">
+        <div class="text-xs text-neutral-200">
+          {{ lastRunSummary.events }} events, duration {{ lastRunSummary.durationMs }} ms
+        </div>
+        <div class="text-xs text-neutral-500">
+          Export the last run to CSV to share with the team.
+        </div>
+      </Callout>
+    </Section>
+
+    <div class="border border-neutral-800/70 rounded-xl bg-neutral-900/60 p-4 shadow-sm lg:col-span-1 space-y-3">
+      <div class="text-sm text-neutral-200">
+        Live traces
+      </div>
+      <div class="text-xs text-neutral-400">
+        Capturing: {{ capturing ? 'yes' : 'no' }}, events: {{ events.length }}
+      </div>
+      <ul class="max-h-64 overflow-auto text-xs text-neutral-300 space-y-1">
+        <li v-for="(event, idx) in events.slice(-20).reverse()" :key="idx">
+          <span class="text-neutral-100 font-mono">{{ event.name }}</span>
+          — {{ (event.duration ?? 0).toFixed(2) }} ms
+          <span v-if="event.meta" class="text-neutral-500"> {{ JSON.stringify(event.meta) }}</span>
+        </li>
+      </ul>
+    </div>
+
+    <Section
+      title="Payload preview"
+      icon="i-solar:code-file-bold-duotone"
+      inner-class="gap-3"
+      class="lg:col-span-2"
+    >
+      <div class="text-xs text-neutral-300">
+        Latest payload
+      </div>
+
+      <div v-if="previewText" class="border border-neutral-700 rounded-lg border-dashed bg-neutral-900/60 p-3 space-y-2">
+        <pre class="max-h-60 overflow-auto whitespace-pre-wrap text-xs text-neutral-200">{{ previewText }}</pre>
+      </div>
+      <div v-else class="text-xs text-neutral-500">
+        Generate a payload to see the preview.
+      </div>
+    </Section>
+  </div>
+</template>
+
+<route lang="yaml">
+meta:
+  layout: settings
+</route>
diff --git a/packages/stage-shared/src/export-csv.ts b/packages/stage-shared/src/export-csv.ts
new file mode 100644
index 000000000..4d9cb91e2
--- /dev/null
+++ b/packages/stage-shared/src/export-csv.ts
@@ -0,0 +1,28 @@
+function quoteField(field: unknown): string {
+  return `"${String(field).replace(/"/g, '""')}"`
+}
+
+function toCsv(rows: Array<Array<unknown>>): string {
+  return rows
+    .map(row => row.map(quoteField).join(','))
+    .join('\n')
+}
+
+export function exportCsv(rows: Array<Array<unknown>>, basename: string) {
+  if (!rows.length)
+    return
+
+  if (typeof Blob === 'undefined' || typeof document === 'undefined' || typeof URL === 'undefined') {
+    console.warn('[CSV] Export is only supported in browser environments')
+    return
+  }
+
+  const csv = toCsv(rows)
+  const blob = new Blob([csv], { type: 'text/csv;charset=utf-8;' })
+  const url = URL.createObjectURL(blob)
+  const link = document.createElement('a')
+  link.href = url
+  link.download = `${basename}-${Date.now()}.csv`
+  link.click()
+  URL.revokeObjectURL(url)
+}
diff --git a/packages/stage-shared/src/index.ts b/packages/stage-shared/src/index.ts
index a7f7eafbc..703d7e71f 100644
--- a/packages/stage-shared/src/index.ts
+++ b/packages/stage-shared/src/index.ts
@@ -1,3 +1,5 @@
 export * from './environment'
+export * from './export-csv'
+export * from './perf/tracer'
 export * from './url'
 export * from './window'
diff --git a/packages/stage-shared/src/perf/tracer.ts b/packages/stage-shared/src/perf/tracer.ts
new file mode 100644
index 000000000..c1fd8117a
--- /dev/null
+++ b/packages/stage-shared/src/perf/tracer.ts
@@ -0,0 +1,154 @@
+export interface TraceEvent {
+  tracerId: string
+  name: string
+  ts: number
+  duration?: number
+  meta?: Record<string, any>
+}
+
+export type TraceSubscriber = (event: TraceEvent) => void
+
+export interface PerfTracer {
+  forceDisable: () => void
+  isEnabled: () => boolean
+  acquire: (token?: string) => () => void
+  release: (token?: string) => void
+  subscribe: (subscriber: TraceSubscriber) => () => void
+  subscribeSafe: (
+    subscriber: TraceSubscriber,
+    options?: { label?: string, onError?: (error: unknown, event: TraceEvent) => void },
+  ) => () => void
+  emit: (event: TraceEvent) => void
+  mark: (tracerId: string, name: string, meta?: Record<string, any>) => void
+  withMeasure: <T>(
+    tracerId: string,
+    name: string,
+    fn: () => Promise<T> | T,
+    meta?: Record<string, any>,
+  ) => Promise<T>
+}
+
+export function createPerfTracer(): PerfTracer {
+  let enabled = false
+  const leases = new Map<string, number>()
+  const subscribers = new Set<TraceSubscriber>()
+
+  function push(event: TraceEvent, force = false) {
+    if (!enabled && !force)
+      return
+
+    for (const subscriber of subscribers)
+      subscriber(event)
+  }
+
+  function recomputeEnabled() {
+    let total = 0
+    for (const count of leases.values())
+      total += count
+    enabled = total > 0
+  }
+
+  function acquire(token = '__default__') {
+    const next = (leases.get(token) ?? 0) + 1
+    leases.set(token, next)
+    recomputeEnabled()
+    return () => release(token)
+  }
+
+  function release(token = '__default__') {
+    const current = leases.get(token) ?? 0
+    if (current <= 1)
+      leases.delete(token)
+    else
+      leases.set(token, current - 1)
+    recomputeEnabled()
+  }
+
+  function forceDisable() {
+    leases.clear()
+    enabled = false
+  }
+
+  function isEnabled() {
+    return enabled
+  }
+
+  function subscribe(subscriber: TraceSubscriber) {
+    subscribers.add(subscriber)
+    return () => subscribers.delete(subscriber)
+  }
+
+  function subscribeSafe(
+    subscriber: TraceSubscriber,
+    options?: { label?: string, onError?: (error: unknown, event: TraceEvent) => void },
+  ) {
+    const wrapped: TraceSubscriber = (event) => {
+      try {
+        subscriber(event)
+      }
+      catch (error) {
+        if (options?.onError)
+          options.onError(error, event)
+        else
+          console.error(`[PerfTracer] subscriber${options?.label ? ` (${options.label})` : ''} threw`, error, event)
+      }
+    }
+    return subscribe(wrapped)
+  }
+
+  function emit(event: TraceEvent) {
+    push(event, false)
+  }
+
+  function mark(tracerId: string, name: string, meta?: Record<string, any>) {
+    push({
+      tracerId,
+      name,
+      ts: performance.now(),
+      meta,
+    }, false)
+  }
+
+  async function withMeasure<T>(
+    tracerId: string,
+    name: string,
+    fn: () => Promise<T> | T,
+    meta?: Record<string, any>,
+  ) {
+    const shouldEmit = enabled
+    if (!shouldEmit)
+      return fn()
+
+    const start = performance.now()
+    try {
+      return await fn()
+    }
+    finally {
+      const disabledAtEnd = !enabled
+      push({
+        tracerId,
+        name,
+        ts: start,
+        duration: performance.now() - start,
+        meta: disabledAtEnd
+          ? { ...meta, tracerDisabledDuringMeasure: true }
+          : meta,
+      }, true)
+    }
+  }
+
+  return {
+    forceDisable,
+    isEnabled,
+    acquire,
+    release,
+    subscribe,
+    subscribeSafe,
+    emit,
+    mark,
+    withMeasure,
+  }
+}
+
+// Default singleton used across surfaces. Devtools should call enable/disable explicitly.
+export const defaultPerfTracer = createPerfTracer()
diff --git a/packages/stage-ui/src/composables/markdown.ts b/packages/stage-ui/src/composables/markdown.ts
index f510a993a..ebc1e92f4 100644
--- a/packages/stage-ui/src/composables/markdown.ts
+++ b/packages/stage-ui/src/composables/markdown.ts
@@ -9,6 +9,7 @@ import remarkMath from 'remark-math'
 import RemarkParse from 'remark-parse'
 import RemarkRehype from 'remark-rehype'
 
+import { defaultPerfTracer } from '@proj-airi/stage-shared'
 import { unified } from 'unified'
 
 // Define a specific, compatible type for our processor to ensure type safety.
@@ -28,6 +29,26 @@ function extractLangs(markdown: string): BundledLanguage[] {
   return [...langs]
 }
 
+function measuredKatex(options?: Parameters<typeof rehypeKatex>[0]) {
+  const transform = rehypeKatex(options)
+  return (tree: any, file: any) => {
+    const start = performance.now()
+    const length = typeof file?.value === 'string' ? file.value.length : undefined
+    try {
+      return transform(tree, file)
+    }
+    finally {
+      defaultPerfTracer.emit({
+        tracerId: 'markdown',
+        name: 'process.katex',
+        ts: start,
+        duration: performance.now() - start,
+        meta: { length },
+      })
+    }
+  }
+}
+
 async function createProcessor(langs: BundledLanguage[]): Promise<MarkdownProcessor> {
   const options: RehypeShikiOptions = {
     themes: {
@@ -42,7 +63,7 @@ async function createProcessor(langs: BundledLanguage[]): Promise<MarkdownProces
     .use(RemarkParse)
     .use(remarkMath)
     .use(RemarkRehype)
-    .use(rehypeKatex, { output: 'mathml' })
+    .use(measuredKatex, { output: 'mathml' })
     .use(rehypeShiki, options)
     .use(RehypeStringify)
 }
@@ -64,42 +85,63 @@ export function useMarkdown() {
     .use(RemarkParse)
     .use(remarkMath)
     .use(RemarkRehype)
-    .use(rehypeKatex, { output: 'mathml' })
+    .use(measuredKatex, { output: 'mathml' })
     .use(RehypeStringify)
 
   return {
     process: async (markdown: string): Promise<string> => {
-      try {
-        // A quick check for code fences. If none, use the fast fallback.
-        if (!/`{3,}/.test(markdown))
-          return fallbackProcessor.processSync(markdown).toString()
+      const hasCodeFence = /`{3,}/.test(markdown)
+      const meta = { length: markdown.length, hasCodeFence }
 
-        const langs = extractLangs(markdown)
+      return defaultPerfTracer.withMeasure('markdown', 'process', async () => {
+        try {
+          // A quick check for code fences. If none, use the fast fallback.
+          if (!hasCodeFence) {
+            return defaultPerfTracer.withMeasure('markdown', 'process.pipeline.basic', () => {
+              return fallbackProcessor.processSync(markdown).toString()
+            }, meta)
+          }
 
-        // Always ensure 'python' is loaded as it's our default.
-        const langSet = new Set(langs)
-        langSet.add('python')
-        const languagesToLoad = Array.from(langSet)
+          const langs = extractLangs(markdown)
 
-        const processor = await getProcessor(languagesToLoad)
-        const result = await processor.process(markdown)
-        return result.toString()
-      }
-      catch (error) {
-        console.warn(
-          'Failed to process markdown with syntax highlighting, falling back to basic processing:',
-          error,
-        )
-        // Fallback to basic processor without highlighting
-        return fallbackProcessor.processSync(markdown).toString()
-      }
+          // Always ensure 'python' is loaded as it's our default.
+          const langSet = new Set(langs)
+          langSet.add('python')
+          const languagesToLoad = Array.from(langSet)
+
+          const processor = await getProcessor(languagesToLoad)
+          const result = await defaultPerfTracer.withMeasure('markdown', 'process.pipeline.rich', () => processor.process(markdown), meta)
+          return result.toString()
+        }
+        catch (error) {
+          console.warn(
+            'Failed to process markdown with syntax highlighting, falling back to basic processing:',
+            error,
+          )
+          // Fallback to basic processor without highlighting
+          return defaultPerfTracer.withMeasure('markdown', 'process.pipeline.fallback', () => {
+            return fallbackProcessor.processSync(markdown).toString()
+          }, { ...meta, fallback: true })
+        }
+      }, meta)
     },
 
     // Synchronous version for backward compatibility
     processSync: (markdown: string): string => {
-      return fallbackProcessor
+      const start = performance.now()
+      const output = fallbackProcessor
         .processSync(markdown)
         .toString()
+
+      defaultPerfTracer.emit({
+        tracerId: 'markdown',
+        name: 'process.pipeline.sync',
+        ts: start,
+        duration: performance.now() - start,
+        meta: { length: markdown.length },
+      })
+
+      return output
     },
   }
 }
diff --git a/packages/stage-ui/src/stores/chat.ts b/packages/stage-ui/src/stores/chat.ts
index 621f3bc03..15fcbf7ee 100644
--- a/packages/stage-ui/src/stores/chat.ts
+++ b/packages/stage-ui/src/stores/chat.ts
@@ -24,6 +24,7 @@ export const CONTEXT_CHANNEL_NAME = 'airi-context-update'
 export const CHAT_STREAM_CHANNEL_NAME = 'airi-chat-stream'
 
 export const useChatStore = defineStore('chat', () => {
+  const llmStore = useLLM()
   const { stream, discoverToolsCompatibility } = useLLM()
   const consciousnessStore = useConsciousnessStore()
   const { activeProvider } = storeToRefs(consciousnessStore)
@@ -239,6 +240,10 @@ export const useChatStore = defineStore('chat', () => {
     return nextGeneration
   }
 
+  function getSessionGenerationValue(sessionId = activeSessionId.value) {
+    return getSessionGeneration(sessionId)
+  }
+
   function generateInitialMessage() {
     // TODO: compose, replace {{ user }} tag, etc
     const content = codeBlockSystemPrompt + mathSyntaxSystemPrompt + systemPrompt.value
@@ -521,7 +526,7 @@ export const useChatStore = defineStore('chat', () => {
       if (shouldAbort())
         return
 
-      await stream(options.model, options.chatProvider, newMessages as Message[], {
+      await llmStore.stream(options.model, options.chatProvider, newMessages as Message[], {
         headers,
         tools: options.tools,
         onStreamEvent: async (event: StreamEvent) => {
@@ -593,6 +598,36 @@ export const useChatStore = defineStore('chat', () => {
     }
   }
 
+  // ----- Remote stream helpers (for broadcast/devtools) -----
+  function beginRemoteStream() {
+    streamingMessage.value = { role: 'assistant', content: '', slices: [], tool_results: [], createdAt: Date.now() }
+  }
+
+  function appendRemoteLiteral(literal: string) {
+    streamingMessage.value.content += literal
+
+    const lastSlice = streamingMessage.value.slices.at(-1)
+    if (lastSlice?.type === 'text') {
+      lastSlice.text += literal
+      return
+    }
+
+    streamingMessage.value.slices.push({
+      type: 'text',
+      text: literal,
+    })
+  }
+
+  function finalizeRemoteStream(fullText?: string) {
+    const sessionId = activeSessionId.value
+    const sessionMessagesForSend = getSessionMessagesById(sessionId)
+    if (streamingMessage.value.slices.length > 0)
+      sessionMessagesForSend.push(toRaw(streamingMessage.value))
+    streamingMessage.value = { role: 'assistant', content: '', slices: [], tool_results: [] }
+    if (fullText)
+      streamingMessage.value.content = fullText
+  }
+
   async function send(
     sendingMessage: string,
     options: SendOptions,
@@ -617,7 +652,7 @@ export const useChatStore = defineStore('chat', () => {
     messages,
     streamingMessage,
 
-    discoverToolsCompatibility,
+    discoverToolsCompatibility: llmStore.discoverToolsCompatibility,
 
     send,
     setActiveSession,
@@ -641,6 +676,12 @@ export const useChatStore = defineStore('chat', () => {
     emitAssistantMessageHooks,
     emitChatTurnCompleteHooks,
 
+    getSessionGenerationValue,
+
+    beginRemoteStream,
+    appendRemoteLiteral,
+    finalizeRemoteStream,
+
     onBeforeMessageComposed,
     onAfterMessageComposed,
     onBeforeSend,
diff --git a/packages/stage-ui/src/stores/markdown-stress.ts b/packages/stage-ui/src/stores/markdown-stress.ts
new file mode 100644
index 000000000..5b170e15c
--- /dev/null
+++ b/packages/stage-ui/src/stores/markdown-stress.ts
@@ -0,0 +1,467 @@
+import type { TraceEvent } from '@proj-airi/stage-shared'
+import type { ChatProvider } from '@xsai-ext/providers/utils'
+
+import type { StreamEvent } from './llm'
+
+import { defaultPerfTracer, exportCsv as exportCsvFile } from '@proj-airi/stage-shared'
+import { defineStore, storeToRefs } from 'pinia'
+import { ref } from 'vue'
+
+import { useChatStore } from './chat'
+import { useLLM } from './llm'
+import { useConsciousnessStore } from './modules/consciousness'
+import { usePerfTracerBridgeStore } from './perf-tracer-bridge'
+import { useProvidersStore } from './providers'
+
+interface DeterministicTimer {
+  now: () => number
+  schedule: (delayMs: number, fn: () => void | Promise<void>) => number
+  cancel: (id: number) => void
+  tick: (ms: number) => Promise<void>
+  clear: () => void
+}
+
+function createDeterministicTimer(startAt = 0): DeterministicTimer {
+  interface Scheduled {
+    id: number
+    at: number
+    fn: () => void | Promise<void>
+  }
+
+  let now = startAt
+  let nextId = 1
+  const queue: Scheduled[] = []
+
+  function schedule(delayMs: number, fn: Scheduled['fn']) {
+    const id = nextId++
+    const at = now + Math.max(0, delayMs)
+    queue.push({ id, at, fn })
+    queue.sort((a, b) => a.at === b.at ? a.id - b.id : a.at - b.at)
+    return id
+  }
+
+  function cancel(id: number) {
+    const index = queue.findIndex(job => job.id === id)
+    if (index !== -1)
+      queue.splice(index, 1)
+  }
+
+  async function tick(ms: number) {
+    const target = now + Math.max(0, ms)
+    while (queue[0]?.at !== undefined && queue[0].at <= target) {
+      const job = queue.shift()!
+      now = job.at
+      await job.fn()
+    }
+    now = target
+  }
+
+  function clear() {
+    queue.length = 0
+    now = 0
+  }
+
+  return {
+    now: () => now,
+    schedule,
+    cancel,
+    tick,
+    clear,
+  }
+}
+
+function chunkText(text: string, size: number) {
+  if (size <= 0)
+    return [text]
+
+  const chunks: string[] = []
+  for (let i = 0; i < text.length; i += size)
+    chunks.push(text.slice(i, i + size))
+
+  return chunks
+}
+
+function createMockStream(options: {
+  scenario: DevtoolsChatScenario
+  timer: DeterministicTimer
+  onEvent: (event: StreamEvent) => void | Promise<void>
+}) {
+  let cancelled = false
+  const {
+    scenario: {
+      assistant: {
+        text,
+        firstTokenDelayMs = 0,
+        rate,
+      },
+    },
+    timer,
+    onEvent,
+  } = options
+
+  const chunks = chunkText(text, Math.max(1, rate?.maxChunkSize ?? 96))
+  const intervalMs = 1000 / Math.max(1, rate?.tokensPerSecond ?? 40)
+
+  async function run() {
+    const yieldMacro = () => new Promise(resolve => setTimeout(resolve, 0))
+    let lastTs = timer.now()
+    const base = lastTs + firstTokenDelayMs
+
+    for (const [idx, chunk] of chunks.entries()) {
+      if (cancelled)
+        return
+      const target = base + idx * intervalMs
+      await timer.tick(target - lastTs)
+      lastTs = target
+      await onEvent({ type: 'text-delta', text: chunk })
+      await yieldMacro()
+    }
+
+    if (cancelled)
+      return
+
+    const finishAt = base + chunks.length * intervalMs
+    await timer.tick(finishAt - lastTs)
+    await onEvent({ type: 'finish' } as StreamEvent)
+  }
+
+  function cancel() {
+    cancelled = true
+  }
+
+  return {
+    run,
+    cancel,
+  }
+}
+
+interface RunSnapshot {
+  startedAt: number
+  stoppedAt: number
+  events: TraceEvent[]
+}
+
+interface DevtoolsChatScenario {
+  userMessages: Array<{ atMs: number, text: string }>
+  assistant: {
+    text: string
+    firstTokenDelayMs?: number
+    rate?: {
+      tokensPerSecond?: number
+      jitterMs?: number
+      maxChunkSize?: number
+    }
+  }
+}
+
+export const useMarkdownStressStore = defineStore('markdownStress', () => {
+  const capturing = ref(false)
+  const events = ref<TraceEvent[]>([])
+  const lastRun = ref<RunSnapshot>()
+  const payloadPreview = ref<string>('')
+  const scheduleDelayMs = ref(10000)
+  const runState = ref<'idle' | 'scheduled' | 'running'>('idle')
+  const scenario = ref<DevtoolsChatScenario | null>(null)
+  const isMock = ref(false)
+  const canRunOnline = ref(true)
+  const mockModelId = 'markdown-stress-mock'
+
+  const providersStore = useProvidersStore()
+  const consciousnessStore = useConsciousnessStore()
+  const { activeProvider, activeModel } = storeToRefs(consciousnessStore)
+  const perfTracerBridge = usePerfTracerBridgeStore()
+
+  let unsubscribe: (() => void) | undefined
+  let startedAt = 0
+  let releaseTracer: (() => void) | undefined
+  let runTimeout: ReturnType<typeof setTimeout> | undefined
+  let autoStopTimeout: ReturnType<typeof setTimeout> | undefined
+  let inFlightTimers: Array<ReturnType<typeof setTimeout>> = []
+  const runCleanups: Array<() => void> = []
+  const mockTimer = createDeterministicTimer()
+  let mockStreamCancel: (() => void) | undefined
+
+  function clearTimers() {
+    if (runTimeout) {
+      clearTimeout(runTimeout)
+      runTimeout = undefined
+    }
+    if (autoStopTimeout) {
+      clearTimeout(autoStopTimeout)
+      autoStopTimeout = undefined
+    }
+    for (const timer of inFlightTimers)
+      clearTimeout(timer)
+    inFlightTimers = []
+    mockStreamCancel?.()
+    mockStreamCancel = undefined
+    mockTimer.clear()
+  }
+
+  function clearRunCleanups() {
+    while (runCleanups.length) {
+      const cleanup = runCleanups.pop()
+      cleanup?.()
+    }
+  }
+
+  function startCapture() {
+    if (capturing.value)
+      return
+
+    capturing.value = true
+    startedAt = performance.now()
+    events.value = []
+
+    unsubscribe = defaultPerfTracer.subscribeSafe((event) => {
+      if (event.tracerId !== 'markdown' && event.tracerId !== 'chat')
+        return
+
+      events.value.push(event)
+    }, { label: 'markdown-stress' })
+    releaseTracer = defaultPerfTracer.acquire('markdown-stress')
+    perfTracerBridge.requestEnable('markdown-stress')
+  }
+
+  function stopCapture() {
+    if (!capturing.value)
+      return
+
+    clearTimers()
+    clearRunCleanups()
+    lastRun.value = {
+      startedAt,
+      stoppedAt: performance.now(),
+      events: [...events.value],
+    }
+
+    unsubscribe?.()
+    unsubscribe = undefined
+    releaseTracer?.()
+    releaseTracer = undefined
+    perfTracerBridge.requestDisable('markdown-stress')
+    capturing.value = false
+    runState.value = 'idle'
+  }
+
+  function buildForFlood() {
+    const line = 'for for for for for'
+    // 800 lines * 5 words = 4000 tokens
+    return Array.from({ length: 800 }, () => line).join('\n')
+  }
+
+  function generateScenario(): DevtoolsChatScenario {
+    const userPrompt = 'Give me a huge stress-test JavaScript block with 2000 occurrences of the keyword `for` wrapped in ```javascript```.'
+    const followUp = 'I really need a JS block containing 2000 `for` keywords — please ensure the request is fully satisfied.'
+    const assistantText = [
+      'Here is a large JS `for` block (line breaks every 5 entries, about 4000 words total):',
+      '```python',
+      buildForFlood(),
+      '```',
+      'Done. This should heavily stress markdown parsing and rendering.',
+    ].join('\n\n')
+
+    return {
+      userMessages: [
+        { atMs: 0, text: userPrompt },
+        { atMs: 1200, text: followUp },
+      ],
+      assistant: {
+        text: assistantText,
+        firstTokenDelayMs: 150,
+        rate: { tokensPerSecond: 120, jitterMs: 5, maxChunkSize: 96 },
+      },
+    }
+  }
+
+  function ensureScenario() {
+    if (!scenario.value)
+      scenario.value = generateScenario()
+    return scenario.value
+  }
+
+  function generatePreview() {
+    const next = generateScenario()
+    scenario.value = next
+    payloadPreview.value = [
+      `User (t=0ms): ${next.userMessages[0].text}`,
+      `User (t=${next.userMessages[1].atMs}ms): ${next.userMessages[1].text}`,
+      '--- Assistant stream ---',
+      next.assistant.text,
+    ].join('\n\n')
+  }
+
+  async function runOnlineScenario() {
+    const chatStore = useChatStore()
+    const targetScenario = ensureScenario()
+
+    const provider = await providersStore.getProviderInstance(activeProvider.value) as ChatProvider | undefined
+    if (!provider || !activeModel.value) {
+      console.warn('[markdown-stress] No active provider/model for online mode')
+      canRunOnline.value = false
+      stopCapture()
+      return
+    }
+    canRunOnline.value = true
+
+    const runStart = performance.now()
+    for (const message of targetScenario.userMessages) {
+      const delay = Math.max(0, runStart + message.atMs - performance.now())
+      const timer = setTimeout(async () => {
+        try {
+          await chatStore.send(message.text, {
+            model: activeModel.value!,
+            chatProvider: provider,
+          })
+        }
+        catch (error) {
+          console.error('[markdown-stress] Online send failed', error)
+        }
+      }, delay)
+      inFlightTimers.push(timer)
+    }
+  }
+
+  async function runMockScenario() {
+    const chatStore = useChatStore()
+    const llm = useLLM()
+    const targetScenario = ensureScenario()
+    const modelToUse = mockModelId
+    const mockProvider: ChatProvider = {
+      chat(model: string) {
+        return {
+          baseURL: 'mock://markdown-stress/',
+          apiKey: '',
+          headers: {},
+          model,
+        } as any
+      },
+    } as ChatProvider
+
+    const originalStream = llm.stream
+    llm.stream = async (_model, _provider, _messages, options) => {
+      const runner = createMockStream({
+        scenario: targetScenario,
+        timer: mockTimer,
+        onEvent: async (event) => {
+          await options?.onStreamEvent?.(event)
+        },
+      })
+      mockStreamCancel = runner.cancel
+      try {
+        await runner.run()
+      }
+      finally {
+        mockStreamCancel = undefined
+      }
+    }
+    runCleanups.push(() => {
+      llm.stream = originalStream
+      mockStreamCancel = undefined
+    })
+
+    const runStart = performance.now()
+    for (const message of targetScenario.userMessages) {
+      const delay = Math.max(0, runStart + message.atMs - performance.now())
+      const timer = setTimeout(async () => {
+        try {
+          await chatStore.send(message.text, {
+            model: modelToUse,
+            chatProvider: mockProvider,
+          })
+        }
+        catch (error) {
+          console.error('[markdown-stress] Mock send failed', error)
+        }
+      }, delay)
+      inFlightTimers.push(timer)
+    }
+  }
+
+  async function scheduleRun() {
+    // if already scheduled, cancel
+    if (runState.value === 'scheduled') {
+      cancelScheduledRun()
+      return
+    }
+
+    // if already running, abort immediately
+    if (runState.value === 'running') {
+      stopCapture()
+      return
+    }
+
+    clearTimers()
+    ensureScenario()
+    runState.value = 'scheduled'
+
+    runTimeout = setTimeout(async () => {
+      runState.value = 'running'
+      runTimeout = undefined
+      startCapture()
+      if (isMock.value)
+        await runMockScenario()
+      else
+        await runOnlineScenario()
+    }, scheduleDelayMs.value)
+
+    autoStopTimeout = setTimeout(() => {
+      stopCapture()
+    }, scheduleDelayMs.value + 60000)
+  }
+
+  function cancelScheduledRun() {
+    clearTimers()
+    clearRunCleanups()
+    runState.value = 'idle'
+  }
+
+  function setMockMode(enabled: boolean) {
+    isMock.value = enabled
+    if (enabled)
+      canRunOnline.value = true
+  }
+
+  function toggleMockMode() {
+    setMockMode(!isMock.value)
+  }
+
+  function exportCsv(snapshot?: RunSnapshot) {
+    const target = snapshot ?? lastRun.value
+    if (!target)
+      return
+
+    const rows: Array<Array<string | number>> = [['tracerId', 'name', 'ts', 'duration', 'meta']]
+    for (const event of target.events) {
+      rows.push([
+        event.tracerId,
+        event.name,
+        event.ts.toFixed(3),
+        event.duration ?? '',
+        JSON.stringify(event.meta ?? {}),
+      ])
+    }
+
+    exportCsvFile(rows, 'markdown-stress')
+  }
+
+  return {
+    canRunOnline,
+    capturing,
+    events,
+    lastRun,
+    payloadPreview,
+    scheduleDelayMs,
+    runState,
+    scenario,
+    isMock,
+    startCapture,
+    stopCapture,
+    scheduleRun,
+    cancelScheduledRun,
+    generatePreview,
+    setMockMode,
+    toggleMockMode,
+    exportCsv,
+  }
+})
diff --git a/packages/stage-ui/src/stores/mods/api/context-bridge.ts b/packages/stage-ui/src/stores/mods/api/context-bridge.ts
index c6fb96d72..e276b4357 100644
--- a/packages/stage-ui/src/stores/mods/api/context-bridge.ts
+++ b/packages/stage-ui/src/stores/mods/api/context-bridge.ts
@@ -21,6 +21,7 @@ export const useContextBridgeStore = defineStore('mods:api:context-bridge', () =
   const { post: broadcastStreamEvent, data: incomingStreamEvent } = useBroadcastChannel<ChatStreamEvent, ChatStreamEvent>({ name: CHAT_STREAM_CHANNEL_NAME })
 
   const disposeHookFns = ref<Array<() => void>>([])
+  let remoteStreamGuard: { sessionId: string, generation: number } | null = null
 
   async function initialize() {
     await mutex.acquire()
@@ -137,9 +138,7 @@ export const useContextBridgeStore = defineStore('mods:api:context-bridge', () =
         isProcessingRemoteStream = true
 
         try {
-          if (event.sessionId && chatStore.activeSessionId !== event.sessionId)
-            chatStore.setActiveSession(event.sessionId)
-
+          // Use the receiver's active session to avoid clobbering chat state when events come from other windows/devtools.
           switch (event.type) {
             case 'before-compose':
               await chatStore.emitBeforeMessageComposedHooks(event.message, event.context)
@@ -149,21 +148,52 @@ export const useContextBridgeStore = defineStore('mods:api:context-bridge', () =
               break
             case 'before-send':
               await chatStore.emitBeforeSendHooks(event.message, event.context)
+              remoteStreamGuard = {
+                sessionId: chatStore.activeSessionId,
+                generation: chatStore.getSessionGenerationValue(),
+              }
+              chatStore.sending = true
+              chatStore.beginRemoteStream()
               break
             case 'after-send':
               await chatStore.emitAfterSendHooks(event.message, event.context)
               break
             case 'token-literal':
+              if (!remoteStreamGuard)
+                return
+              if (remoteStreamGuard.sessionId !== chatStore.activeSessionId)
+                return
+              if (chatStore.getSessionGenerationValue(remoteStreamGuard.sessionId) !== remoteStreamGuard.generation)
+                return
+              chatStore.appendRemoteLiteral(event.literal)
               await chatStore.emitTokenLiteralHooks(event.literal, event.context)
               break
             case 'token-special':
               await chatStore.emitTokenSpecialHooks(event.special, event.context)
               break
             case 'stream-end':
+              if (!remoteStreamGuard)
+                break
+              if (remoteStreamGuard.sessionId !== chatStore.activeSessionId)
+                break
+              if (chatStore.getSessionGenerationValue(remoteStreamGuard.sessionId) !== remoteStreamGuard.generation)
+                break
               await chatStore.emitStreamEndHooks(event.context)
+              chatStore.finalizeRemoteStream()
+              chatStore.sending = false
+              remoteStreamGuard = null
               break
             case 'assistant-end':
+              if (!remoteStreamGuard)
+                break
+              if (remoteStreamGuard.sessionId !== chatStore.activeSessionId)
+                break
+              if (chatStore.getSessionGenerationValue(remoteStreamGuard.sessionId) !== remoteStreamGuard.generation)
+                break
               await chatStore.emitAssistantResponseEndHooks(event.message, event.context)
+              chatStore.finalizeRemoteStream(event.message)
+              chatStore.sending = false
+              remoteStreamGuard = null
               break
           }
         }
diff --git a/packages/stage-ui/src/stores/perf-tracer-bridge.ts b/packages/stage-ui/src/stores/perf-tracer-bridge.ts
new file mode 100644
index 000000000..9132b5f8a
--- /dev/null
+++ b/packages/stage-ui/src/stores/perf-tracer-bridge.ts
@@ -0,0 +1,142 @@
+import type { TraceEvent } from '@proj-airi/stage-shared'
+
+import { defaultPerfTracer } from '@proj-airi/stage-shared'
+import { useBroadcastChannel } from '@vueuse/core'
+import { defineStore } from 'pinia'
+import { watch } from 'vue'
+
+type PerfTracerMode = 'forward' | 'receive'
+type PerfTracerState = 'idle' | PerfTracerMode
+
+interface PerfTracerMessageEnable {
+  type: 'enable'
+  token?: string
+  origin: string
+  mode?: PerfTracerMode
+}
+
+interface PerfTracerMessageDisable {
+  type: 'disable'
+  token?: string
+  origin: string
+}
+
+interface PerfTracerMessageEvent {
+  type: 'event'
+  event: TraceEvent
+  origin: string
+}
+
+type PerfTracerMessage = PerfTracerMessageEnable | PerfTracerMessageDisable | PerfTracerMessageEvent
+
+const PERF_TRACER_CHANNEL = 'airi-perf-tracer'
+const RELAY_META_KEY = '__perfTracerRelayedFrom'
+const BRIDGE_TOKEN = 'perf-bridge'
+
+export const usePerfTracerBridgeStore = defineStore('perfTracerBridge', () => {
+  const instanceId = Math.random().toString(36).slice(2, 10)
+  const { post, data } = useBroadcastChannel<PerfTracerMessage, PerfTracerMessage>({ name: PERF_TRACER_CHANNEL })
+
+  let release: (() => void) | undefined
+  let unsubscribe: (() => void) | undefined
+  let state: PerfTracerState = 'idle'
+
+  function enableLocal(token = BRIDGE_TOKEN) {
+    if (release)
+      return
+    release = defaultPerfTracer.acquire(token)
+  }
+
+  function disableLocal() {
+    release?.()
+    release = undefined
+  }
+
+  function startForwarding() {
+    if (unsubscribe)
+      return
+    unsubscribe = defaultPerfTracer.subscribeSafe((event) => {
+      if (event.tracerId !== 'markdown' && event.tracerId !== 'chat')
+        return
+      if (event.meta?.[RELAY_META_KEY])
+        return
+      post({
+        type: 'event',
+        event: {
+          ...event,
+          meta: { ...event.meta, [RELAY_META_KEY]: instanceId },
+        },
+        origin: instanceId,
+      })
+    }, { label: 'perf-bridge' })
+  }
+
+  function stopForwarding() {
+    unsubscribe?.()
+    unsubscribe = undefined
+  }
+
+  function transition(next: PerfTracerState, token = BRIDGE_TOKEN) {
+    if (state === next)
+      return
+    if (next === 'idle') {
+      stopForwarding()
+      disableLocal()
+    }
+    else if (next === 'receive') {
+      enableLocal(token)
+      stopForwarding()
+    }
+    else if (next === 'forward') {
+      enableLocal(token)
+      startForwarding()
+    }
+    state = next
+  }
+
+  watch(data, (message) => {
+    if (!message)
+      return
+    if (message.origin === instanceId)
+      return
+
+    if (message.type === 'enable') {
+      const mode: PerfTracerMode = message.mode ?? 'forward'
+      const token = message.token ?? BRIDGE_TOKEN
+      transition(mode, token)
+    }
+    else if (message.type === 'disable') {
+      transition('idle')
+    }
+    else if (message.type === 'event') {
+      if (state === 'idle')
+        return
+      // Replay remote events into the local tracer; requires tracer enabled to pass through.
+      const relayedFrom = message.event.meta?.[RELAY_META_KEY] ?? message.origin
+      defaultPerfTracer.emit({
+        ...message.event,
+        meta: { ...message.event.meta, [RELAY_META_KEY]: relayedFrom },
+      })
+    }
+  })
+
+  function requestEnable(token?: string, mode: PerfTracerMode = 'forward', localState: PerfTracerState = mode) {
+    const tokenToUse = token ?? BRIDGE_TOKEN
+    transition(localState, tokenToUse)
+    post({ type: 'enable', token: tokenToUse, origin: instanceId, mode })
+  }
+
+  function requestDisable(token?: string) {
+    transition('idle')
+    post({ type: 'disable', token: token ?? BRIDGE_TOKEN, origin: instanceId })
+  }
+
+  return {
+    requestEnable,
+    requestDisable,
+    enableLocal,
+    disableLocal,
+    startForwarding,
+    stopForwarding,
+  }
+})
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 630576a3c..e36760923 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -1239,6 +1239,9 @@ importers:
       '@proj-airi/stage-layouts':
         specifier: workspace:^
         version: link:../../packages/stage-layouts
+      '@proj-airi/stage-shared':
+        specifier: workspace:^
+        version: link:../../packages/stage-shared
       '@proj-airi/stage-ui':
         specifier: workspace:^
         version: link:../../packages/stage-ui